Poliomyelitis

Poliomyelitis is a viral infectious disease leading to relatively more or less severe and diffuse forms of paralysis. It can rapidly lead to death mainly in cases of 'great' damage of respiratory nature, or to complete recovery or remain undetectable, which do not hinder its contagious potential. In its paralytic form, this condition leads to motor impairment. This disease, which used to be a scourge in the 1940s and 1950s, has almost completely disappeared from industrialized countries and most part of the world. This disease is possibly the second viral disease to be eradicated through vaccination after smallpox.

What is poliomyelitis?

The disease name was derived from two Greek terms: polios, meaning 'grey', and muelos, meaning 'marrow'. It indeed affects the grey matter of the anterior part of the bone marrow, the anterior horns, that is controlling motor function. Poliomyelitis is also referred to as acute anterior poliomyelitis (AAP), Heine-Medin's disease, infantile spinal paralysis, etc.

The poliomyelitic infection primarily involves an extreme attraction of the virus for the large motor cells of the anterior horn (sometimes also for cranial nerve motor nuclei). Some of the affected cells will never reach the inflammatory stage, which explains why spectacular remissions occur in some conditions, but many will not be spared. In addition, the pool of nerve cells cannot be renewed if damaged. This explains the extremely high variability of the paralysis, most frequently of asymmetric nature or even completely irregular, reflecting random distribution of the viral attacks and impaired motor units (unit of muscle fibres innervated by a single motor neuron, the cell body of which is the anterior horn).

Existing since the old times, poliomyelitis has long been considered a sporadic disease (in some isolated cases) primarily affecting young children. This condition had showed high epidemic potential for more than a century, sparing no age groups and considered in the 1940s and 1950s as one of the most dreadful calamities (up to 4,500 cases annually in France). The first vaccination campaigns started in the 1950s against three known types of viruses, at first with a killed vaccine (Salk – 1954, injectable) followed by a live attenuated vaccine (Sabin – 1957, orally).

In 1988, the World Health Organization (WHO) launched a global initiative to eradicate poliomyelitis by the year 2000. The number of cases has not ceased to decrease ever since, which proves that the WHO team has been able to deliver the goods. In 1992 and 1993, the number of reported cases of poliomyelitis shrunk again by half (from 16,000 to 8,000) and the number of countries in which no cases were reported has constantly increased. While Western Europe and Australia had not reported any cases for several years (except for those reported by some sects refusing vaccination), the American continent had also been completely spared in 1993. The disease has lost ground in nearly every country of the world, even in Northwest Africa where no new cases were reported. However, poliomyelitis vaccination remained highly recommended.

How does poliomyelitis occur?

The onset is most frequently sudden, influenza-like (resembling a simple flu) with back and neck pain. A few days later, paralysis sets in when the fever has gone down.

Complementary examinations provides guidance for diagnosis: lumbar puncture shows an inflammatory response; traces of the virus can be found in feces when the examination is performed at an early stage.

How is it progressing?

Three aspects can be distinguished: the disease itself, its deforming potential, and the controversial existence of a post-polio syndrome.

The disease itself

The stage of regression of paralysis is ill defined in terms of both cause and duration. Some anterior horn cells only experience temporary difficulties in their functional relationships. But how can be explained the reactive oedema and vascular disorders? What is certain is that an 'orphan' motor unit, which has lost its cell, is sometimes almost brought back to life by a neighbour cell that the virus has spared. This is called the capture phenomena, which is revealed on the EMG by abnormally large motor units.

The disease's progression is monitored, including the progression of certain muscles under the effect of an active physical therapy treatment based on manual muscle testing, which is a simple grading system that enables the grading of each muscle on a scale ranging from zero, for total paralysis, to five, for normal strength.

A functional prognosis of recovery may then be established early enough: it is common knowledge that muscles remaining at the zero level after one month have very poor chance of becoming useful again, and none at all after six months. Knowledge of the key muscles involved in lower limb stability allows looking at the paralysis map to get a sufficiently good idea of the functional prognosis. They are the gluteus maximus, the triceps surae, and the quadriceps; the gluteus medius acting in the pelvis balance; the abdominal spinal and respiratory muscles at the trunk level; depressor muscles of the shoulder and triceps involved in the support necessary in using a cane; and radial biceps, as well as muscles of the thumb-index grip for prehension.

Final impairments may vary a lot according to variations in the viral attack: from total independence without respiratory aid, every clinical presentation is possible.

Life expectancy is surely very close to normal and many individuals have lived beyond 80 years old, even in cases of very severe disabilities.

Deforming potential

At the outset, disability caused by deformities can be more disturbing than paralysis per se. This is particularly true if the onset of the disease occurred at a young age.

What are the causes of deformities?

Painful muscle shortening: a long time underestimated, muscular pain is yet relatively common in the initial phase and exacerbated by tensioning the muscle concerned. This results in disturbance of the mobilization and engages the individual in resting his muscles (most often feet in extension, knees or hips in flexion, hips in abduction, elbows in flexion, etc.) and musculotendinous shorthening will develop on these painful structures.

Imbalances caused by paralysis: each body part is usually equipped with tension bands ('strings') enabling joints to move in different directions. The most common example is the flexor-extensor antagonistic couple. Whether one of the two muscle groups is paralyzed, for example extensors, the body part will most frequently be in flexion and most likely to remain more or less completely in this position.

Effects of early weight-bearing exercises mobilizing muscles that have not sufficiently recovered and joints for which tension bands are not sufficiently strong.

Growth is virtually always a powerful aggravating factor. According to the old Wolff's law, growth will slow down where there are excessive joint constraints, but on the contrary be enhanced on the side in which the joint tends to open. In other words, as soon as a deformity takes shape during childhood, osseous asymmetry is formed and can only aggravate spontaneously.

There is a vast range of possible deformities: clubfeet of all kinds, hip flexum and luxation, pelvic obliquity, clubhand with ulnar or radial deviation, thoracic deformities, etc. Back deformities, cyphosis and scoliosis can also be mentioned, as they often used to be aggravated to the point of causing a respiratory, and sometimes cardiac failures in the long run. Today, treatments that are more refined are performed earlier and prevent this progression. However, it is also common knowledge today that the natural progression of scoliosis does not stop after the child's growth is completed. In fact, the angulation will increase by a mean of one degree and a half annually during adulthood, which explains the need to monitor during a prolonged period and the development of more or less late surgical stabilization.

Finally, slowdown in growth of paralyzed muscles sometimes leads to significant and disturbing shortenings and tend to be combined with circulatory and trophic disorders in extremities: atrophy, cyanosis, coldness, sometimes ulceration, and oedemas. In the latter case, wearing compression stockings may be indicated (put in the morning after the swelling has gone in decubitus).

Why is it controversial?

Signs and symptoms on which the diagnosis is based are allegedly not typical of the condition: atrophy and/or early and relatively sudden onset of muscular impairment, fatigability, signs of recent enervation reflected by EMG. However, the initial condition of the muscle is unknown, while strength is considered normal with only 50% of motor units recruited, it can still be useful with 5 to 10%. On the other hand, initial damage may affect more muscles than showed clinically and the latter are weaker.

Post-polio syndrome can be influenced by many factors known to precipitate malfunctioning. These factors include trauma, weight gain, excessive muscular effort, prolonged bedrest, immobilization due to fracture, increased deformity or inappropriate bracing increasing constraint and effort levels, onset of an arthropathy such as hip arthrosis and cervical arthrosis most likely to lead to impairments of the upper limbs, change of place to live (less stairs), purchase of a car reducing opportunities to walk, etc. How is aging involved? If a number of PPS are reported before age 60, it is just a matter of localized wear or aging of a specific organ, and not generalized aging. The motor unit capital of the normal individual hides unavoidable small physiological losses, which the individual with poliomyelitis cannot afford in terms of functioning.

Finally, the most credible explanation of PPS, which is otherwise rare, would currently be the following: some neurons weakened by a clinically undetectable impairment or receptor neurons responsible for abnormally large motor units would cease to ensure the proper metabolic needs of their axonal branching pattern after a number of years. This would result in enervation of a number of muscular fibres and in neuromuscular conduction disorders, the first sign of which might be the excessive fatigability observed in these patients.

Why is the PPS so discussed and what did it achieve?

In the early 1960's, the rapid trend towards the use of vaccination in western countries put an end to the development of outbreaks of poliomyelitis. The number of new cases dropped to the point that, from that time, rehabilitation physicians were not trained for treating poliomyelitis anymore. Consequently two or three decades later, when these physicians had ceased to practice, the 'old poliomyelitis patients' could not find anyone to consult about their condition anymore. They became alarmed, came together to express their needs for training and information. The second generation of physicians became interested, and books and journals dedicated articles or entire issues to this topic. A real network was increasingly formed which ensured advice provision and reassured former patients who no longer felt abandoned. The pattern of this knowledge network could be an example for other disabling diseases as they will be on the verge of disappearing.

What are the suggested treatments and management strategies?

Initial stage

No medical treatment has any effect on either viral infection or pain. When pain is so intense that it causes insomnia, only the ingestion of sufficient doses of coffee can help getting back to sleep again. The combination of pain and shortening is the enemy against who are used hot packs and baths, passive mobilization combining soft and resistant techniques, as well as positioning with cushions and straps. This shows the importance of the early detection of shortening trends and the high hazard of nursing errors that generate improper alignments by authorizing patients to seat too early or for prolonged periods.

At the initial stage, one cannot disregard the problems raised by acute respiratory diseases by indicating the use of intubation, tracheotomy, or even iron lung, the availability of which was scarce during the height of the epidemic.

Acute stage

This stage has always been part of the physician's purview; surgeons would intervene often, but only later, and there was a long transition period during which no one was appointed responsible for monitoring. The rehabilitation spirit introduced precocity, continuity and coordination concerns in treatments, which were desperately needed. This was a new dimension added to treatments actually based on very simple principles: based on an exhaustive muscle and joint testing regularly performed, facilitating the awakening and progress of deficient muscles, preventing deformities by fighting shortening trends and positional asymmetry, spacing the exercises of seating and standing positions, as well as walking. According to those assessments and to attitudes observed during testing with or without temporary aids, these principles become: seeking to achieve maximum independency in activities of daily living for patients, with technical aids if necessary, addressing psychosocial, school or occupational dimensions early in the process, as well as the eventual home conversion in order to reduce to a minimum the 'disruption shock' caused by the paralyzing insult.

As bracing and technical aids are discussed in other articles of this encyclopedia, this topic will not be treated exhaustively. They are an important part of the treatment of poliomyelitis, which has actually contributed a lot to their development. It appears useful to remind that bracing in individuals with poliomyelitis does not generally go along well with modern kit trends and their making should remain traditional. As for the other techniques, they range from small thumb opposition slings made of tissue or thermoformed to the most sophisticated computerized aids that allow, for example, to fit a respirator on a powered wheelchair, or environmental controls enabling the use of a telephone or a tape recorder, as well as the control of door openings, etc.

In this vast program directed by the rehabilitation physician, physical therapists play an important role, but occupational therapists, artificial limb fitters, educators and facilitators, as well as social workers and nurses also have a role to play in the team spirit where information and guidance of the patient and his/her family are not forgotten. After a certain while and for a long time, the use of orthopedic surgery may be necessary to re-establish segment-specific balance, for muscle graft or tendon lengthening, to straighten a spinal curvature or stabilize a joint, etc.

Is maintenance treatment necessary?

'Medicalizing' what cannot be is futile. However, once rehabilitation is deemed over, the following reasons may lead to go on with or reinitiate the maintenance treatment:

In the face of reduced respiratory capacity, it is recommended to undertake respiratory rehabilitation two or three times per week. Brief episodes of suspended breathing during the night, insomnia, shortness of breath while talking, morning fatigue, should lead to an assessment. In cases of respiratory failure, it is recommended to masticate slowly and talking only in between swallowing in order to avoid chocking on food. Finally, influenza vaccination before each winter is highly recommended to all individuals with poliomyelitis who have respiratory conditions.

When some key muscles get weaker, because they were not sufficiently used despite having recovered enough to ensure function, for example, by limited walking. Functional electrostimulation is not performed without some hazards, as it may cause exhaustion of the muscle, which is intended to be reinforced. This is why this method is not undertaken until the physician has given his/her advice based on muscle testing, which provides a better knowledge of the muscle's condition.

Every time complications arise and result in immobilization (fracture, intercurrent diseases), it is necessary to resume the rehabilitation treatment in order to bring muscles back to their previous condition.

If the patient is to be hospitalized without emergency, it is appropriate to discuss previously with the physician about modalities in order to ensure greater comfort to the patient. Home care service should be given the authorization to pursue care at the hospital.

Can risk of deformities justify maintenance treatment? In children, surely, but less likely in adults for whom it is generally desirable to plan natural postures that will go against the deforming trend, if possible. Thus, the paralyzed individual who cannot walk and find himself/herself seating in a wheelchair all day and lying on the side with flexed legs all night is facing risks of hip or knee flexum as he/she never works out these parts in extension. If the individual lies prone to sleep or performs only one hour of weight-bearing exercises in extension per day, the risk of flexum will vanish.

As in the case of physicians and for the same purpose, there are only a few physical therapists who have a strong knowledge of poliomyelitis. It is thus appropriate to rely upon rehabilitation centers every time it is possible, because they usually have outside associates whose competence in that matter is well known.

Living with poliomyelitis

Nearly all individuals who had poliomyelitis need rehabilitation during their lifetime. Steps are not always easy to accomplish. After many efforts deployed in resuming gait without aids, the individual is forced to use them, or yet, canes are tossed aside at the cost of many hip swings and significant efforts to resume walking, but one or two canes must be used in the end. The individual might have been spared to use a wheelchair, but this is something that must be achieved in the end. The use of manual wheelchairs might have been considered in particular, but now the individual must choose between a more restrictive life inside and the use of a powered wheelchair. Assisted ventilation might have been abandoned, but the individual must use a respirator at night. These examples might be coupled with decisions that were postponed to the fullest extent possible. Opting for a mixed solution, even if it is transient, facilitates habilitation: for instance the use of a cane indoors and wheelchair outdoors.

Poliomyelitic women are able to carry a pregnancy to term with a few precautions according to their anatomical distribution of paralysis.

As for personal health practices, they are a matter of common sense: find a good balance between activity and rest, avoid gaining weight, fatigue cramps or prolonged exertional pain, protect oneself against cold conditions, practice swimming in warm water a few times per week if possible, avoid postponing habilitation measures that are required, be wary of any persistent muscular weakening following intense prolonged activity, reduce the occupational activity related to fatigue if necessary (or compatible with one's employment), have spare aids or wheelchair, constant projects and humor.